44.
Johnson is hired by a company to see if a new product, Topocal, will cause hair to grow on
the heads of bald men. He recruits one thousand bald men and randomly divides them into
two groups: Five hundred men (group A) rub Topocal on their scalps each day; the other
five hundred (group B) rub a standard skin lotion on their scalps each day. After two
months, Johnson checks to see what the results have been. He finds that there has been
hair growth in 7 percent of group A and in 2 percent of group B.
What is the sample?
A.
bald men in general
B.
the bald men who participated in the study
C.
the men in group A
D.
the men in group B
Accessibility: Keyboard Navigation
45.
Johnson is hired by a company to see if a new product, Topocal, will cause hair to grow on
the heads of bald men. He recruits one thousand bald men and randomly divides them into
two groups: Five hundred men (group A) rub Topocal on their scalps each day; the other
five hundred (group B) rub a standard skin lotion on their scalps each day. After two
months, Johnson checks to see what the results have been. He finds that there has been
hair growth in 7 percent of group A and in 2 percent of group B.
What is the population?
A.
bald men in general
B.
the bald men who participated in the study
C.
the men in group A
D.
the men in group B
Accessibility: Keyboard Navigation
46.
Johnson is hired by a company to see if a new product, Topocal, will cause hair to grow on
the heads of bald men. He recruits one thousand bald men and randomly divides them into
two groups: Five hundred men (group A) rub Topocal on their scalps each day; the other
five hundred (group B) rub a standard skin lotion on their scalps each day. After two
months, Johnson checks to see what the results have been. He finds that there has been
hair growth in 7 percent of group A and in 2 percent of group B.
Given the size of Johnson’s two groups, would you say that the results of the test are
statistically significant?
A.
yes
B.
no
C.
no way to tell
Accessibility: Keyboard Navigation
47.
Johnson is hired by a company to see if a new product, Topocal, will cause hair to grow on
the heads of bald men. He recruits one thousand bald men and randomly divides them into
two groups: Five hundred men (group A) rub Topocal on their scalps each day; the other
five hundred (group B) rub a standard skin lotion on their scalps each day. After two
months, Johnson checks to see what the results have been. He finds that there has been
hair growth in 7 percent of group A and in 2 percent of group B.
If there is a control group here, it is
A.
bald men in general.
B.
the bald men who participated in the study.
C.
the men in group A.
D.
the men in group B.
E.
there is no control group in this study.
48.
Johnson is hired by a company to see if a new product, Topocal, will cause hair to grow on
the heads of bald men. He recruits one thousand bald men and randomly divides them into
two groups: Five hundred men (group A) rub Topocal on their scalps each day; the other
five hundred (group B) rub a standard skin lotion on their scalps each day. After two
months, Johnson checks to see what the results have been. He finds that there has been
hair growth in 7 percent of group A and in 2 percent of group B.
What if Johnson had started with 2,000 bald men (1,000 in each group) and got the same 7
and 2 percent figures? Would this have made any difference for the significance of
Johnson’s results?
A.
Yes: It changes them from insignificant to significant.
B.
Yes: It changes them from significant to insignificant.
C.
No: They were insignificant before, and this leaves them that way.
D.
No: They were significant before, and this leaves them that way.
Accessibility: Keyboard Navigation
49.
Johnson is hired by a company to see if a new product, Topocal, will cause hair to grow on
the heads of bald men. He recruits one thousand bald men and randomly divides them into
two groups: Five hundred men (group A) rub Topocal on their scalps each day; the other
five hundred (group B) rub a standard skin lotion on their scalps each day. After two
months, Johnson checks to see what the results have been. He finds that there has been
hair growth in 7 percent of group A and in 2 percent of group B.
The category that best fits this study is
A.
prospective observational study.
B.
retrospective observational study.
C.
randomized controlled experiment.
Accessibility: Keyboard Navigation
11–24
True / False Questions
50.
The claim “Fluoridated water prevents tooth decay,” if true, implies that fluoridated water
would prevent tooth decay in the majority of individuals who use it.
FALSE
Accessibility: Keyboard Navigation
51.
The claim “Fouled spark plugs kept the car from starting” implies that the car would have
started if the spark plugs had not been fouled.
TRUE
Accessibility: Keyboard Navigation
52.
In a prospective observational study, the members of the experimental group are exposed
to the suspected causal agent by the investigators.
FALSE
Accessibility: Keyboard Navigation
53.
In a retrospective observational study,
none
of the members of the control group show the
effect of the cause being investigated.
TRUE
Accessibility: Keyboard Navigation
11–25
Essay Questions
54.
Evaluate the following analogical argument:
The stock market has made huge gains during each of the past four years. I’m willing to
put my money on the claim that it will do the same this coming year.
We are too, but only a
little
of our money. There are too many reasons why the market can
do well for a while and then do very poorly indeed.
55.
Evaluate the following analogical argument:
When Halley’s comet appeared a few years ago, there was an upsurge in the number of
suicides across the country. The same thing happened when the Hale-Bopp comet
appeared in 1997. I’ll bet the next appearance of a visible comet will produce a rash of
suicides.
We think this is a pretty good argument, but it would be improved by a larger sample.
56.
Evaluate the following analogical argument:
We have visited seven cities in southern Spain, and every one of them has a bull ring. I’ll
bet there’s one in the next Spanish city we visit.
Not such a good argument. It might be that bullfights are more popular in some regions of
the country than in others or that the visits were only to moderately wealthy towns (biased
sample).
57.
Evaluate the following analogical argument:
I like Fuji apples; I’ll bet Fuji pears are good too.
We’re not so sure. There are all kinds of reasons that both fruits could be called “Fuji,”
including simply that they were first produced near the famous Japanese mountain. If our
speaker said he liked every pear he’d ever eaten, he’d have a much better argument than
this one.
58.
Evaluate the following analogical argument:
Prostitution is legal in the Netherlands, and it doesn’t seem to produce any terrible
societal problems. I’ll bet it would be the same in the United States.
We aren’t convinced. There are lots of cultural differences between the two countries, and
they weaken the argument. (We might add, it isn’t so clear that the premise about
problems in the Netherlands is true, since the influence of criminal activities is being felt
in the prostitution business.)
59.
Evaluate the following analogical argument:
Hey, Coach! I know somebody good for our volleyball team. Her name is Stacy, and she
hasn’t played much volleyball, but she’s a great basketball player.
Someone good at basketball is unlikely to be terrible at volleyball. Good analogical
argument.
60.
Evaluate the following analogical argument:
Can I recommend a good mechanic? Sure—B&M Tuneup. I’ve been taking my car there for
years, and I’ve never had a single complaint. Of course, I have an old Chevy, and you drive
a Mazda—one of those rotary-engine jobs, isn’t it?
It is reasonable to expect good service from a mechanic who has given years of good
service to a friend, but you cannot be certain that the mechanic who knows Chevys will be
very good with your rotary-engine Mazda—as the speaker implies.
61.
Rank the following analogical arguments:
a. Look, our stereo is a Panasonic and so is our TV, and we’ve never had any trouble with
either of them. Let’s get the Panasonic answering machine. Why take chances?
b. Look, our stereo is Japanese and so is our TV, and we’ve never had any trouble with
either of them. Let’s get the Japanese answering machine. Why take chances?
c. Look, Frank’s answering machine is a Panasonic and so is Heather’s, and they both say
they’ve never had trouble with them. Let’s get the Panasonic answering machine. Why
take chances?
c (the strongest), then a, then b.
62.
Evaluate the following analogical argument:
The thing that worries me is that we’re going to get bogged down in Iraq just as we got
bogged down in Vietnam. The situations are exactly the same: It’s us against a poor nation
that is determined to win and doesn’t play by the rules our military thinkers understand.
Weak argument. The situations certainly aren’t exactly the same.
63.
Evaluate the following analogical argument:
The Patriots easily made it into last year’s Super Bowl. They’ll have almost the same
personnel next year, so I’m putting my money on the Patriots to be back next year.
The Patriots’ having almost the same personnel next year helps the analogy some, but too
many other relevant factors have to be considered before this argument would be a safe
one—the other teams may not have the same personnel they had last year, for instance.
Notice that it’s easy to confuse what a person is betting on in cases like this. It’s one thing
for the Patriots to be the team most likely to play in the championship game; it’s another
for it to be more likely that they’ll play than that they won’t.
64.
Evaluate the following analogical argument:
He: Let’s leave Cincinnati for the golden West! Why don’t we move to Los Angeles?
She: Well, for one thing, we couldn’t afford to buy a house there.
He: Don’t be such a pessimist. We bought this house here, didn’t we? How much more
expensive can houses in Los Angeles be?
Even if he is not aware of the difference in the cost of housing in the two cities, he should
realize there are important relevant differences between such different parts of the
country that could profoundly affect housing costs. Furthermore, if they bought their
Cincinnati house quite a while ago, the changes that have since occurred in the real estate
market can make a great difference in either or both localities. Note that the argument
would be just as shaky if the inference were from Los Angeles to Cincinnati. (The fact that
housing costs are currently higher in Los Angeles than in Cincinnati is irrelevant to the
strength of the argument, though it proves that the implied conclusion is false.)
65.
Evaluate the following analogical argument:
Six months ago, several of Molly’s friends joined the Trimtime Fitness Center. Each of
them participated in Trimtime’s weight-reduction and fitness regimen. All reported
substantial weight reduction, and all are visibly slimmer. Molly is convinced. She joins
Trimtime and enrolls in the same program, hoping and expecting to see the same results.
She is especially delighted to learn that Trimtime had adjusted its program to make it even
more effective in a shorter period of time.
Molly should consider potential differences between her and her friends. From our
outsider’s point of view, though, we would have to say that if she followed the original
program just as they did, then we would expect her to get similar results. But without
knowing the details of the changes in the program or the evidence for believing that the
changes will be an improvement, Molly should not be delighted to learn that the program
has been “adjusted”; the change in the program weakens the argument. (Trimtime might,
of course, be able to give Molly good reason for thinking that the change will be an
improvement.)
66.
Evaluate the following analogical argument:
Wolfgang has been to America, once visiting New York and once visiting Columbus.
(Why
is it always “Columbus, Ohio”? Is there another sizable Columbus?)
Now he has an
opportunity to visit New Orleans. Wolfgang decides not to go. “Based on my experience, it
will be awful—there’ll be crime, violence, poverty, rude people, drug addicts—every kind of
unpleasantness.”
Wolfgang’s reasoning is really to this effect: He didn’t like New York or Columbus, so he
wouldn’t like any other U.S. city. And we would expect Wolfgang not to like New Orleans,
even though there are tremendous differences among the cities mentioned in the exercise.
If he’s offended by Columbus, he’ll be righteously indignant about New Orleans!
67.
Evaluate the following analogical argument:
In Great Britain, savings of between 20 and 40 percent in costs have resulted from selling
government-run programs and businesses to individuals and companies in the private
sector. This argues well for the administration’s interest in selling such U.S. government
entities as the Bonneville Power Administration, the Tennessee Valley Authority, and
various parts of the postal service.
The terms of the analogy are not clear: Which (or at least what kind of) British programs
and businesses were sold off? Would the sales be handled similarly (with regard to terms
of payments, for example)? Would the government subsidize private ownership for a
period of time after the sale? How would general differences in the economic structures of
the United States and Great Britain affect the argument? There are too many differences
68.
Evaluate the following analogical argument:
From a letter to the editor: “Harry Kryshnah lost the last election because he supported
handgun control. So now he’s changed his tune and claims he’ll be the first one to oppose
handgun control. I voted for him last June, but I won’t vote for him this time, and it’s not
because I favor handgun control. I just don’t want a governor who can talk out of both
sides of his mouth like that.”
This is not an ad hominem. This is the writer’s argument: People I’ve met and most people
who are unprincipled in one way, were unprincipled in others; therefore, Kryshnah, who is
a member of this class, is apt to be unprincipled in other ways, too. Given the premises,
the argument is not a weak one; however, a premise that assigns a person to a class of
unprincipled people because of a change in position is one that needs close examination.
Is the change due to a lack of principle? Or was it occasioned by legitimate reasoning that
was not self-serving?
69.
Evaluate the following analogical argument:
Mr. Naphal has read in an authoritative science report that a dye commonly injected into
Florida oranges is carcinogenic. He resolves not only to avoid Florida oranges until he
learns that they no longer are dyed with the same chemical, but also to avoid California
oranges and all grapefruit as well.
We’d avoid California oranges too, unless we had some reason to think they weren’t dyed
with the same dye. But the fact that grapefruit are a different color (and thus would
require different colored dyes) weakens the argument.
70.
Evaluate the following analogical argument:
“He won the Silver Medal of Honor, has a Purple Heart, and was an Eagle Scout. I find it
difficult to believe that it was he who committed the robbery.”
Even though few of us know people who have won all these awards, most of us do have
experience with people who have earned acknowledgment for dedication, respect for
others, courage, conscientiousness, and so on. These people are the “premise-analogue.”
Because we know (and know of) few such people who also commit deeds that deny these
virtues, we reason that this individual is unlikely to have done so. The analogical reasoning
encountered here is inherently weaker than any direct evidence that bears on the person’s
evidence.
71.
Evaluate the following analogical argument:
A conversation:
“You going to vote for Spankey or Howard in the city council election?”
“Howard. As far as I can make out, their experience is the same, and they both take about
the same position on the issues. But Spankey was a student of mine. I caught him
cheating once.”
Our experience tells us that most people who are dishonest in one situation are more apt
to be dishonest in another; so, everything else being equal between the two candidates, it
72.
Evaluate the following analogical argument:
Hank Kingscote has won every one of his fifteen previous prizefights by knockouts. The
chances are that the poor fellow who’s going to fight him next will wind up stretched out
on the canvas.
Prizefights are a lot like snowflakes and political elections: the next one is not necessarily
going to look like the last one(s). We know nothing about the opponents in Hank’s
previous fights (the premise-analogue) nor about his upcoming opponent (the fight with
whom is the population).
73.
Evaluate the following analogical argument:
According to a 2008 National Safety Council study, hunting has the lowest rate of injury of
the 22 most popular recreational activities. Get this: Badminton, yes, badminton! Four
times as many injuries as hunting.
The presence of a gun in one of the recreational activities makes this analogy a faulty one,
since the types of injuries are not comparable.
74.
Evaluate the following analogical argument:
Clark said gun control should not be blamed in situations when the user abuses the
weapon. “A gun is an inanimate object,” he said. “A plane is an inanimate object, but look
at how many people are killed by them and they’re not illegal.” Clark said that he was
raised on a ranch and has “run around with guns since I was big enough to carry them.” He
added that he has never shot anybody as a result of growing up around guns.
Clark’s analogy involves inanimate objects that are too dissimilar. He then generalizes too
hastily from his own experience with being raised around guns.
75.
Evaluate the following analogical argument:
Washburn has read that it is good to include cabbage in one’s diet. He doesn’t care much
for cabbage, but he likes brussels sprouts. Since the latter look like small cabbages, he
assumes that their nutritional benefits will be about the same as those of cabbage.
Obviously, there may be differences between cabbages and brussels sprouts that are
highly important from a nutritional standpoint. Nevertheless, the clear physical similarities
between the two vegetables make this a fair analogical argument.
76.
Evaluate the following generalization(s), identifying sample, population, attribute of
interest, and the extent to which the claims involved are knowable. Consider carefully the
size and diversification of the sample and the extent to which the population differs or
may differ from the sample; remember, what’s important is that the sample be
representative.
Stratton takes one look at his new teacher and concludes he is going to like the course.
“You can just tell,” he says to his girlfriend later, “it’s gonna be a great course. The teacher
brought up all these interesting subjects—and it was only the first day.”
Hasty generalization, although we don’t think the reasoning is all bad. Even from one
meeting, Stratton is probably able to tell a good bit about whether he likes to listen to this
particular teacher, and such things can make a course more enjoyable.
77.
Evaluate the following generalization(s), identifying sample, population, attribute of
interest, and the extent to which the claims involved are knowable. Consider carefully the
size and diversification of the sample and the extent to which the population differs or
may differ from the sample; remember, what’s important is that the sample be
representative.
The cocktail Beatrice orders before dinner is watery, so she decides not to eat there after
all. “Don’t think they can fix decent dinners if they can’t even make a decent martini,” she
mutters.
Hasty generalization.
78.
Evaluate the following generalization(s), identifying sample, population, attribute of
interest, and the extent to which the claims involved are knowable. Consider carefully the
size and diversification of the sample and the extent to which the population differs or
may differ from the sample; remember, what’s important is that the sample be
representative.
Parker recommends the latest Larry McMurtry novel to Moore. Moore decides not to
bother, since every other novel Parker has recommended turned out to be a dud, in
Moore’s opinion.
If the list of duds is a long one, no fallacy.
79.
Evaluate the following generalization(s), identifying sample, population, attribute of
interest, and the extent to which the claims involved are knowable. Consider carefully the
size and diversification of the sample and the extent to which the population differs or
may differ from the sample; remember, what’s important is that the sample be
representative.
Fong notes that the pavement deteriorates as he crosses into the next county. “Guess
they don’t keep up their roads very well,” he thinks.
Hasty generalization.
11–39
80.
Evaluate the following generalization(s), identifying sample, population, attribute of
interest, and the extent to which the claims involved are knowable. Consider carefully the
size and diversification of the sample and the extent to which the population differs or
may differ from the sample; remember, what’s important is that the sample be
representative.
Stortz has heard from his friends that the folks in North Carolina are pretty friendly, so he
looks forward to going through it on his bike trip to Florida.
Biased generalization, because the sample of opinion isn’t likely to be representative; most
people he’s heard from are likely to have been reporting on their friends in North Carolina.
81.
Evaluate the following generalization(s), identifying sample, population, attribute of
interest, and the extent to which the claims involved are knowable. Consider carefully the
size and diversification of the sample and the extent to which the population differs or
may differ from the sample; remember, what’s important is that the sample be
representative.
Noting that recent scientific research suggests that a daily glass of wine or two might be
good for the heart, Mr. Laub decides to tank up. “Why in hell not,” he says. “If one glass of
wine is good for you, most likely five or six is
really
good for you.”
Hasty generalization.
11–40
82.
Evaluate the following generalization(s), identifying sample, population, attribute of
interest, and the extent to which the claims involved are knowable. Consider carefully the
size and diversification of the sample and the extent to which the population differs or
may differ from the sample; remember, what’s important is that the sample be
representative.
“How come the people in these big motor homes always have a couple of midget dogs
with them,” Jasper wonders.
Hasty generalization.
83.
Evaluate the following generalization(s), identifying sample, population, attribute of
interest, and the extent to which the claims involved are knowable. Consider carefully the
size and diversification of the sample and the extent to which the population differs or
may differ from the sample; remember, what’s important is that the sample be
representative.
Victor has just heard somewhere that regular injections of testosterone help improve the
memories of men his age, but he can’t recall where he heard it. “Probably was on the TV
news,” he figures. “I don’t read the newspaper very often.”
No fallacy.